Page 97 - DCAP312_WEB_TECHNOLOGIES_II

Unit 5: Database Access

Data Source=C:/Workers.mdb”; Notes
Con.Close();
MessageBox.Show( “Database Closed”);
Con.Dispose();
}
Run your programme and you should see the two message boxes display. The form will display
after you click OK on these.
Do not calls Close or Dispose on a Connection, a DataReader, or any other
managed object in the Finalize method of your class. In a finalizer, you should
only release unmanaged resources that your class owns directly. If your class
does not own any unmanaged resources, do not include a Finalize method
in your class definition.

5.3 Database Command

Commands are issued next to databases to receive trial against data stores and to include any
declaration that can be issued adjacent to a database. You can use the OleDbCommand or the
SqlCommand classes to get a command to your data store, and OleDbCommand can be precise
to the data stock up The SqlClient class (to connect to a computer that is running Microsoft SQL
Server) and the OleDb class (for any database that has an OLE DB or ODBC driver available)
within ADO.NET. However, the code is generally the same for both.

With ADO, you can issue commands through the Command, the Connection, or the Recordset
object. In ADO.NET, only the Command objects (SqlCommand or OleDbCommand) run
commands.
To run a command, follow these steps:

Follow these steps to create a new console application in Microsoft Visual C# 2005 or in Microsoft
Visual C# .NET:
• Start Microsoft Visual Studio 2005 or Microsoft Visual Studio .NET.

• On the File menu, point to New, and then click Project.
• In the New Project dialog box, click Visual C# Projects under Project Types, and then click
Console Application under Templates.
Make sure that your project contains a reference to the System.Data namespace, and add a
reference if it does not.
Use the using statement on the System and System.Data namespaces so that you do not have to
qualify declarations in those namespaces later in your code. You can also include System.Data.
SqlClient or System.Data.OleDb, depending on which one you are using.
using System;
using System.Data;
using System.Data.SqlClient;
Before you can create a connection to a database, you must have a connection string. Connection
strings contain all of the information that you need to establish a database connection, including
the server name, the database name, the user ID, and the password. For example, the following
connection string points to a local computer that is running SQL Server:

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